1. Field of the Invention
The present invention relates to a valve for regulating a gas flow of the type having a valve housing with an inlet for the gas to be regulated and an outlet for a regulated gas flow, a valve seat with a valve opening, and a movable sealing actuator having a controllable shaft, wherein the terminal side of the sealing part can influence a seal element arranged between the valve seat and the sealing part such that the sealing actuator closes and opens the valve opening and regulates the gas flow through the valve opening.
2. Description of the Prior Art
A valve of this type is depicted and described in U.S. Pat. No. 5,265,594. In connection with the supplying of gas to a patient connected to a breathing device it is very important that large as well as small amounts of gas be regulated with high precision and reproducibility by means of such a valve. Ideally to achieve this it is necessary that the seal element, which is a membrane drawn tight at the valve housing in the value of this reference, be lifted parallel to the valve seat in the opening thereof, and be pressed against the valve seat by the shaft end of the actuator with a uniformly distributed force in the closing of said valve seat. Even if such a shaft--a solenoid shaft in this reference--causes the membrane to follow an apparently perfect pattern of motion such as this, problems can arise, particularly in connection with the opening of the valve opening, when the membrane is supposed to come loose from the valve seat. For example, problems can arise as a result of wear or aging of the membrane, and if the membrane gets hung up in a first instant of movement and then abruptly opens, whereby a precise and repeated control of the flow can be difficult to achieve, particularly in connection with small amounts. The delay or the hysteresis which can arise in the magnetization of the solenoid shaft in the activation thereof can also cause an undesirable control of the gas flow in connection with the opening of the valve opening, with the abovementioned adverse effects.